U.S. patent application number 10/955430 was filed with the patent office on 2006-03-30 for absorbent composite having selective regions for improved attachment.
Invention is credited to Gabriel Hammam Adam, Barry Anthony Fitzsimons, Davis Dang Hoang Nhan, David Martin Jackson, Michael Donald Sperl, Hoa La Wilhelm.
Application Number | 20060069365 10/955430 |
Document ID | / |
Family ID | 35759027 |
Filed Date | 2006-03-30 |
United States Patent
Application |
20060069365 |
Kind Code |
A1 |
Sperl; Michael Donald ; et
al. |
March 30, 2006 |
Absorbent composite having selective regions for improved
attachment
Abstract
An absorbent composite has at least one first region and at
least one second region. The first region includes an elastomeric
polymer at a first concentration and at least one absorbent
material, such as superabsorbent material, and the second region
includes an elastomeric polymer at a second concentration. The
absorbent composite can provide improved attachment within an
absorbent article, such as a stretchable absorbent article, even
after fluid loading, while maintaining suitable absorbent
properties.
Inventors: |
Sperl; Michael Donald;
(Waupaca, WI) ; Hoang Nhan; Davis Dang; (Appleton,
WI) ; Adam; Gabriel Hammam; (Alpharetta, GA) ;
Jackson; David Martin; (Alpharetta, GA) ; Fitzsimons;
Barry Anthony; (Cummings, GA) ; Wilhelm; Hoa La;
(Appleton, WI) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
US
|
Family ID: |
35759027 |
Appl. No.: |
10/955430 |
Filed: |
September 30, 2004 |
Current U.S.
Class: |
604/370 ;
604/368 |
Current CPC
Class: |
A61F 13/539
20130101 |
Class at
Publication: |
604/370 ;
604/368 |
International
Class: |
A61F 13/15 20060101
A61F013/15 |
Claims
1. An absorbent composite comprising at least one first region and
at least one second region, wherein said first region comprises an
absorbent material and a first elastomeric polymer at a first
concentration, and said second region comprises a second
elastomeric polymer at a second concentration, wherein said second
concentration is higher than said first concentration.
2. The absorbent composite of claim 1 wherein said first
elastomeric polymer is different from said second elastomeric
polymer.
3. The absorbent composite of claim 1 wherein said at least one
second region has a higher dry peel strength than said at least one
first region.
4. The absorbent composite of claim 1 wherein said at least one
second region has a higher wet peel strength than said at least one
first region.
5. The absorbent composite of claim 1 wherein said absorbent
material comprises at least a superabsorbent material.
6. The absorbent composite of claim 5 wherein said at least one
first region comprises about 40-percent by weight or greater
superabsorbent material and about 15-percent by weight or less
elastomeric polymer, and wherein said at least one second region
comprises greater than about 30-percent by weight elastomeric
polymer.
7. The absorbent composite of claim 6 wherein said at least one
first region comprises about 65-percent by weight or greater
superabsorbent material.
8. The absorbent composite of claim 6 wherein said at least one
first region comprises about 85-percent by weight or greater
superabsorbent material
9. The absorbent composite of claim 6 wherein said at least one
second region comprises about 70-percent by weight or greater
elastomeric polymer.
10. The absorbent composite of claim 6 wherein said at least one
second region comprises about 90-percent by weight or greater
elastomeric polymer.
11. The absorbent composite of claim 1 wherein said at least one
second region is located on an edge portion of said absorbent
composite.
12. The absorbent composite of claim 11 wherein said at least one
second region is continuous from a distal end portion of said
absorbent composite to an opposing distal end portion of said
absorbent composite.
13. The absorbent composite of claim 1 wherein said absorbent
material comprises at least a fiber selected from the group
consisting of natural fibers and synthetic fibers.
14. The absorbent composite of claim 1 wherein said at least one
second region has a total surface area of about 50-percent or less
than a total surface area of said absorbent composite.
15. The absorbent composite of claim 1 wherein said at least one
second region has a total surface area of about 30-percent or less
than a total surface area of said absorbent composite.
16. The absorbent composite of claim 1 wherein at least a portion
of said at least one first region is located in at least one target
zone of said absorbent composite.
17. The absorbent composite of claim 1 wherein said at least one
second region is located outside at least one target zone of said
absorbent composite.
18. The absorbent composite of claim 1 wherein said at least one
first region has a first wet peel strength and said at least one
second region has a second wet peel strength, wherein a ratio of
said second wet peel strength value to said first wet peel strength
value is greater than 1.
19. The absorbent composite of claim 1 wherein said at least one
first region has a first wet peel strength and said at least one
second region has a second wet peel strength, wherein a ratio of
said second wet peel strength value to said first wet peel strength
value is greater than 100.
20. The absorbent composite of claim 1 wherein said at least one
first region has a first dry peel strength and said at least one
second region has a second dry peel strength, wherein a ratio of
said second dry peel strength value to said first dry peel strength
value is greater than 1.
21. The absorbent composite of claim 1 wherein said at least one
first region has a first dry peel strength and said at least one
second region has a second dry peel strength, wherein a ratio of
said second dry peel strength value to said first dry peel strength
value is greater than 5.
22. An absorbent composite comprising at least one first region and
at least one second region, wherein said at least one first region
comprises about 60-percent by weight or greater superabsorbent
material, about 35-percent by weight or less hydrophilic fibers,
and about 15-percent by weight or less elastomeric polymer, wherein
said at least one second region comprises about 80-percent by
weight or greater elastomeric polymer, and wherein said second
region is in the form of rectangular strips which run along at
least two opposing edges of said absorbent composite.
23. The absorbent composite of claim 22 having a shape selected
from the group consisting of rectangular shape, triangular shape,
oval shape, race-track shape, I-shape, generally hourglass shape,
and T-shape.
24. An absorbent article comprising: A backsheet A topsheet, and An
absorbent composite comprising at least one first region and at
least one second region, wherein said first region comprises an
absorbent material and a first elastomeric polymer at a first
concentration, and said second region comprises a second
elastomeric polymer at a second concentration, wherein said second
concentration is higher than said first concentration.
25. The absorbent article of claim 24 wherein said absorbent
composite is attached to said absorbent article at said at least
one second region by an attachment means selected from the group
consisting of ultrasonic, pressure, adhesive, sewing, autogenous,
heat, hook-and-loop, and combinations thereof.
26. The absorbent article of claim 24 wherein said absorbent
composite is attached to at least one of said topsheet and said
backsheet.
Description
BACKGROUND
[0001] The present invention relates to an absorbent composite.
More particularly, the present invention pertains to an absorbent
composite which can be incorporated into a variety of absorbent
articles, including personal care products, health/medical
products, and household/industrial products, for example.
[0002] Conventional absorbent composites are typically not
stretchable. However, elastomeric materials have been incorporated
into various structural components of absorbent articles to help
achieve better fit, greater comfort, and enhanced containment.
Adding stretchability to absorbent composites can be difficult
because elastomeric materials often are not absorbent, and the
addition of elastomeric materials to absorbent composites may
inhibit the fluid handling properties of the absorbent composites.
As a result, additional amounts of absorbent materials, such as
superabsorbent materials, may be utilized to counter these
effects.
[0003] Existing absorbent composites can also experience other
disadvantages, such as attachment strength degradation,
particularly after fluid insults. For example, an absorbent
composite incorporated into an absorbent article can detach itself
from the article in either a dry state due to user's motion, for
instance, or in a wet state in which the composite can swell,
resulting in reduced overall bonding strength between the absorbent
composite and the article. For a stretchable article utilizing a
stretchable absorbent composite, this detachment may cause the
composite not to stretch appropriately during use, resulting in
poor fit and discomfort. Such a reduction in attachment performance
can become more significant as the amount of absorbent materials
increases. Therefore, there is a desire for optimizing attachment
of an absorbent composite to an absorbent article. There is also a
desire to optimize attachment of an absorbent composite, such as a
stretchable absorbent composite, to a stretchable article. There is
a further desire to provide a stretchable absorbent composite which
provides a user with good fit and comfort.
SUMMARY
[0004] The present invention concerns an absorbent composite that
can be used in a disposable absorbent article, such as a training
pant. Generally stated, the present invention provides an absorbent
composite including a quantity of an absorbent material operatively
contained within a matrix of elastomeric polymer fibers.
Specifically disclosed is an absorbent composite which has at least
one first region and at least one second region. The first region
includes an elastomeric polymer at a first concentration and at
least one absorbent material, such as superabsorbent material, and
the second region comprises an elastomeric polymer at a second
concentration. In particular aspects, the absorbent composite
provides improved attachment within an absorbent article, such as a
stretchable absorbent article, even after fluid loading. This can
result in greater performance of the article as well as greater
comfort and confidence among the user.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The foregoing and other features, aspects and advantages of
the present invention will become better understood with regard to
the following description, appended claims and accompanying
drawings where:
[0006] FIG. 1 is a perspective view of one embodiment of an
absorbent article that may be made in accordance with the present
invention;
[0007] FIG. 2 is a plan view of the absorbent article shown in FIG.
1 with the article in an unfastened, unfolded and laid flat
condition showing the surface of the article that faces the wearer
when worn and with portions cut away to show underlying
features;
[0008] FIG. 3A is a plan view of an absorbent composite made in
accordance with the present invention;
[0009] FIG. 3B is a cross-section view of an absorbent composite
made in accordance with the present invention;
[0010] FIGS. 4A-4G are plan views of absorbent composites made in
accordance with the present invention;
[0011] FIG. 5 is a representative process and apparatus for
producing an absorbent composite in accordance with the present
invention;
[0012] FIG. 6 is a side view of a die configuration of a
representative apparatus for producing an absorbent composite in
accordance with the present invention; and
[0013] FIG. 7 is a top view of a die configuration of a
representative apparatus for producing an absorbent composite in
accordance with the present invention.
[0014] Repeated use of reference characters in the present
specification and drawings is intended to represent the same or
analogous features or elements of the present invention.
DEFINITIONS
[0015] It should be noted that, when employed in the present
disclosure, the terms "comprises," "comprising" and other
derivatives from the root term "comprise" are intended to be
open-ended terms that specify the presence of any stated features,
elements, integers, steps, or components, and are not intended to
preclude the presence or addition of one or more other features,
elements, integers, steps, components, or groups thereof.
[0016] The phrase "absorbent article" refers to devices which can
absorb and contain body fluids, and more specifically, refers to
devices which are placed against or near the skin to absorb and
contain the various fluids discharged from the body. The term
"disposable" is used herein to describe absorbent articles that are
not intended to be laundered or otherwise restored or reused as an
absorbent article after a single use. Examples of such disposable
absorbent articles include, but are not limited to, personal care
absorbent articles, health/medical absorbent articles, and
household/industrial absorbent articles.
[0017] The term "coform" is intended to describe a blend of
meltblown fibers and cellulose fibers that is formed by air forming
a meltblown polymer material while simultaneously blowing
air-suspended cellulose fibers into the stream of meltblown fibers.
The coform material may also include other materials, such as
superabsorbent materials. The meltblown fibers containing wood
fibers are collected on a forming surface, such as provided by a
foraminous belt. The forming surface may include a gas-pervious
material, such as spunbonded fabric material, that has been placed
onto the forming surface.
[0018] The terms "elastomeric" and "elastic" are used
interchangeably to refer to a material or composite that exhibits
properties which approximate the properties of natural rubber. The
elastomeric material is generally capable of being stretched or
otherwise deformed, and then recovering a significant portion of
its shape after the stretching or deforming force is removed.
[0019] The term "fluid-impermeable" when used to describe a layer
or laminate means that fluid such as water or bodily fluids will
not pass substantially through the layer or laminate under ordinary
use conditions in a direction generally perpendicular to the plane
of the layer or laminate at the point of fluid contact.
[0020] The phrase "health/medical absorbent article" includes a
variety of professional and consumer health-care products
including, but not limited to, products for applying hot or cold
therapy, medical gowns (i.e., protective and/or surgical gowns),
surgical drapes, caps, gloves, face masks, bandages, wound
dressings, wipes, covers, containers, filters, disposable garments
and bed pads, medical absorbent garments, underpads, and the
like.
[0021] The phrase "household/industrial absorbent articles" include
construction and packaging supplies, products for cleaning and
disinfecting, wipes, covers, filters, towels, disposable cutting
sheets, bath tissue, facial tissue, nonwoven roll goods,
home-comfort products including pillows, pads, cushions, masks and
body care products such as products used to cleanse or treat the
skin, laboratory coats, cover-alls, trash bags, stain removers,
topical compositions, laundry soil/ink absorbers, detergent
agglomerators, lipophilic fluid separators, and the like.
[0022] The term "hydrophobic" refers to a material having a contact
angle of water in air of at least 90 degrees. In contrast, as used
herein, the term "hydrophilic" refers to a material having a
contact angle of water in air of less than 90 degrees. For the
purposes of this application, contact angle measurements are
determined as set forth in Robert J. Good and Robert J. Stromberg,
Ed., in "Surface and Colloid Science--Experimental Methods," Vol.
II, (Plenum Press, 1979), herein incorporated by reference in a
manner consistent with the present disclosure.
[0023] The term "layer" when used in the singular can have the dual
meaning of a single element or a plurality of elements.
[0024] The phrase "meltblown fibers" refers to fibers formed by
extruding a molten thermoplastic material through a plurality of
fine, usually circular, die capillaries as molten threads or
filaments into a high velocity, usually heated, gas (e.g., air)
stream which attenuates the filaments of molten thermoplastic
material to reduce their diameter. Thereafter, the meltblown fibers
are carried by the high velocity gas stream and are deposited on a
collecting surface to form a web of randomly disbursed meltblown
fibers.
[0025] The terms "nonwoven" and "nonwoven web" refer to materials
and webs of material having a structure of individual fibers or
filaments which are interlaid, but not in an identifiable manner as
in a knitted fabric. The terms "fiber" and "filament" are used
herein interchangeably. Nonwoven fabrics or webs have been formed
from many processes such as, for example, meltblowing processes,
spunbonding processes, air laying processes, and bonded carded web
processes. The basis weight of nonwoven fabrics is usually
expressed in ounces of material per square yard (osy) or grams per
square meter (gsm) and the fiber diameters are usually expressed in
microns. (Note that to convert from osy to gsm, multiply osy by
33.91.)
[0026] By the terms "particle," "particles," "particulate,"
"particulates" and the like, it is meant that the material is
generally in the form of discrete units. The units can comprise
flakes, fibers, agglomerates, granules, powders, spheres,
pulverized materials or the like, as well as combinations thereof.
The particles can have any desired shape such as, for example,
cubic, rod-like, polyhedral, spherical or semi-spherical, rounded
or semi-rounded, angular, irregular, etc. Shapes having a large
greatest dimension/smallest dimension ratio, like needles, flakes
and fibers, are also contemplated for inclusion herein. The terms
"particle" or "particulate" may also include an agglomeration
comprising more than one individual particle, particulate or the
like. Additionally, a particle, particulate or any desired
agglomeration thereof may be composed of more than one type of
material.
[0027] The term "nonwoven" refers to a fabric web that has a
structure of individual fibers or filaments which are interlaid,
but not in an identifiable repeating manner.
[0028] The phrase "personal care absorbent article" includes, but
is not limited to, absorbent articles such as diapers, diaper
pants, baby wipes, training pants, absorbent underpants, child care
pants, swimwear, and other disposable garments; feminine care
products including sanitary napkins, wipes, menstrual pads,
menstrual pants, panty liners, panty shields, interlabials,
tampons, and tampon applicators; adult-care products including
wipes, pads such as breast pads, containers, incontinence products,
and urinary shields; clothing components; bibs; athletic and
recreation products; and the like.
[0029] The term "polymers" includes, but is not limited to,
homopolymers, copolymers, such as for example, block, graft, random
and alternating copolymers, terpolymers, etc. and blends and
modifications thereof. Furthermore, unless otherwise specifically
limited, the term "polymer" shall include all possible
configurational isomers of the material. These configurations
include, but are not limited to isotactic, syndiotactic and atactic
symmetries.
[0030] The terms "spunbond" or "spunbonded fiber" refer to fibers
which are formed by extruding filaments of molten thermoplastic
material from a plurality of fine, usually circular, capillaries of
a spinneret, and then rapidly reducing the diameter of the extruded
filaments.
[0031] The term "superabsorbent" refers to a water-swellable,
water-insoluble organic or inorganic material capable, under the
most favorable conditions, of absorbing at least about 10 times its
weight, or at least about 15 times its weight, or at least about 25
times its weight in an aqueous solution containing 0.9 weight
percent sodium chloride. The superabsorbent materials can be
natural, synthetic, and modified natural polymers and materials. In
addition, the superabsorbent materials can be inorganic materials,
such as silica gels, or organic compounds such as cross-linked
polymers. The superabsorbent material may be biodegradable or
non-biodegradable. A material is "absorbent" if it absorbs at least
five times its weight of the aqueous solution under these
conditions. The superabsorbent materials can also be incorporated
in a structure by in-situ polymerization.
[0032] The term "target zone" refers to an area of an absorbent
composite where it is desirable for the majority of a fluid insult,
such as urine, menses, or bowel movement, to initially contact. In
particular, for an absorbent composite with one or more fluid
insult points in use, the target zone refers to the area of the
absorbent composite extending a distance equal to 15-percent of the
total length of the composite from each insult point in both
directions.
[0033] These terms may be defined with additional language in the
remaining portions of the specification.
DETAILED DESCRIPTION
[0034] The present invention concerns an absorbent composite that
can be used in an absorbent article, suitably a disposable
absorbent article, such as a training pant. Generally stated, the
present invention provides an absorbent composite including a
quantity of an absorbent material operatively contained within a
matrix of elastomeric polymer fibers. More particularly, the
absorbent composite has at least one first region and at least one
second region, where the first region includes an elastomeric
polymer at a first concentration and at least one absorbent
material, such as a superabsorbent material, and the second region
includes an elastomeric polymer at a second concentration. In
particular aspects, the absorbent composite provides improved
attachment within an absorbent article, such as a stretchable
absorbent article, even after fluid loading. This can result in
improved performance of the article, as well as greater comfort and
confidence among the user.
[0035] Disposable absorbent articles typically include a fluid
pervious topsheet, a backsheet joined to the topsheet, and an
absorbent composite positioned and held between the topsheet and
the backsheet. An absorbent article may also include other
components, such as fluid wicking layers, fluid intake layers,
fluid distribution layers, transfer layers, barrier layers,
wrapping layers and the like, as well as combinations thereof.
[0036] Referring to FIGS. 1 and 2 for exemplary purposes, a
training pant which may incorporate the present invention is shown.
It is understood that the present invention is suitable for use
with various other absorbent articles, including but not limited to
other personal care absorbent articles, health/medical absorbent
articles, household/industrial absorbent articles, and the like
without departing from the scope of the present invention.
[0037] Various materials and methods for constructing training
pants are disclosed in PCT Patent Application WO 00/37009 published
Jun. 29, 2000 by A. Fletcher et al; U.S. Pat. No. 4,940,464 issued
Jul. 10, 1990 to Van Gompel et al.; U.S. Pat. No. 5,766,389 issued
Jun. 16, 1998 to Brandon et al.; and U.S. Pat. No. 6,645,190 issued
Nov. 11, 2003 to Olson et al. which are incorporated herein by
reference to the extent they are consistent herewith.
[0038] FIG. 1 illustrates a training pant in a partially fastened
condition, and FIG. 2 illustrates a training pant in an opened and
unfolded state. The training pant defines a longitudinal direction
48 that extends from the front of the training pant when worn to
the back of the training pant. Opposite to the longitudinal
direction is a lateral direction 49.
[0039] The pair of training pants defines a front region 22, a back
region 24, and a crotch region 26 extending longitudinally between
and interconnecting the front and back regions. The pant also
defines an inner surface adapted in use (e.g., positioned relative
to the other components of the pant) to be disposed toward the
wearer, and an outer surface opposite the inner surface. The
training pant has a pair of laterally opposite side edges and a
pair of longitudinally opposite waist edges.
[0040] The illustrated pant 20 may include a chassis 32, a pair of
laterally opposite front side panels 34 extending laterally outward
at the front region 22 and a pair of laterally opposite back side
panels 134 extending laterally outward at the back region 24.
[0041] Referring to FIGS. 1 and 2, the chassis 32 includes an outer
cover 40 and a bodyside liner 42 that may be joined to the outer
cover 40 in a superimposed relation therewith by adhesives,
ultrasonic bonds, thermal bonds or other conventional techniques.
The chassis 32 may further include the absorbent composite 44 of
the present invention such as shown in FIG. 2 disposed between the
outer cover 40 and the bodyside liner 42 for absorbing fluid body
exudates exuded by the wearer, and may further include a pair of
containment flaps 46 secured to the bodyside liner 42 or the
absorbent composite 44 for inhibiting the lateral flow of body
exudates.
[0042] The outer cover 40, the inner liner 42 and the absorbent
composite 44 may be made from many different materials known to
those skilled in the art. All three layers, for instance, may be
extensible and/or elastomerically extensible. Further, the stretch
properties of each layer may vary in order to control the overall
stretch properties of the product.
[0043] The outer cover 40, for instance, may be breathable and/or
may be liquid impermeable. The outer cover 40 may be constructed of
a single layer, multiple layers, laminates, spunbond fabrics,
films, meltblown fabrics, elastic netting, microporous webs, bonded
card webs or foams provided by elastomeric or polymeric materials.
The outer cover 40, for instance, can be a single layer of a liquid
impermeable material, or alternatively can be a multi-layered
laminate structure in which at least one of the layers is liquid
impermeable.
[0044] The outer cover 40 can be biaxially extensible and
optionally biaxially elastic. Elastic non-woven laminate webs that
can be used as the outer cover 40 include a non-woven material
joined to one or more gatherable non-woven webs, films, or foams.
Stretch Bonded Laminates (SBL) and Neck Bonded Laminates (NBL) are
examples of elastomeric composites.
[0045] Examples of suitable nonwoven materials are
spunbond-meltblown fabrics, spunbond-meltblown-spunbond fabrics,
spunbond fabrics, or laminates of such fabrics with films, foams,
or other nonwoven webs. Elastomeric materials may include cast or
blown films, foams, meltblown fabrics or spunbond fabrics composed
of polyethylene, polypropylene, or polyolefin elastomers, as well
as combinations thereof. The elastomeric materials may include
PEBAX elastomer (available from Atofina Chemicals, Inc., a business
having offices located in Philadelphia, Pa. U.S.A), HYTREL
elastomeric polyester (available from Invista, a business having
offices located in Wilmington, Del. U.S.A.), KRATON elastomer
(available from Kraton Polymers, a business having offices located
in Houston, Tex., U.S.A.), or strands of LYCRA elastomer (available
from Invista), or the like, as well as combinations thereof. The
outer cover 40 may include materials that have elastomeric
properties through a mechanical process, printing process, heating
process, or chemical treatment. For example, such materials may be
apertured, creped, neck-stretched, heat activated, embossed, and
micro-strained; and may be in the form of films, webs, and
laminates.
[0046] Example of a suitable material for a biaxially stretchable
outer cover 40 is a breathable elastic film/nonwoven laminate,
described in U.S. Pat. No. 5,883,028, issued to Morman et al.,
incorporated herein by reference to the extent that it is
consistent herewith. Examples of materials having two-way
stretchability and retractability are disclosed in U.S. Pat. No.
5,116,662 issued to Morman and U.S. Pat. No. 5,114,781 issued to
Morman, each of which is hereby incorporated herein by reference to
the extent that it is consistent herewith. These two patents
describe composite elastic materials capable of stretching in at
least two directions. The materials have at least one elastic sheet
and at least one necked material, or reversibly necked material,
joined to the elastic sheet at least at three locations arranged in
a nonlinear configuration, so that the necked, or reversibly
necked, web is gathered between at least two of those
locations.
[0047] The bodyside liner 42 is suitably compliant, soft-feeling,
and non-irritating to the wearer's skin. The bodyside liner 42 is
also sufficiently liquid permeable to permit liquid body exudates
to readily penetrate through its thickness to the absorbent
composite 44. A suitable bodyside liner 42 may be manufactured from
a wide selection of web materials, such as porous foams,
reticulated foams, apertured plastic films, woven and non-woven
webs, or a combination of any such materials. For example, the
bodyside liner 42 may include a meltblown web, a spunbonded web, or
a bonded-carded-web composed of natural fibers, synthetic fibers or
combinations thereof. The bodyside liner 42 may be composed of a
substantially hydrophobic material, and the hydrophobic material
may optionally be treated with a surfactant or otherwise processed
to impart a desired level of wettability and hydrophilicity.
[0048] The bodyside liner 42 may also be extensible and/or
elastomerically extensible. Suitable elastomeric materials for
construction of the bodyside liner 42 can include elastic strands,
LYCRA elastics, cast or blown elastic films, nonwoven elastic webs,
meltblown or spunbond elastomeric fibrous webs, as well as
combinations thereof. Examples of suitable elastomeric materials
include KRATON elastomers, HYTREL elastomers, ESTANE elastomeric
polyurethanes (available from Noveon, a business having offices
located in Cleveland, Ohio U.S.A.), or PEBAX elastomers. The
bodyside liner 42 can also be made from extensible materials as are
described in U.S. Pat. No. 6,552,245 filed on May 3, 2000 by
Roessler et al. which is incorporated herein by reference to the
extent that it is consistent herewith. The bodyside liner 42 can
also be made from biaxially stretchable materials as described in
U.S. Pat. No. 6,641,134 filed on Oct. 27, 2000 by Vukos et al.
which is incorporated herein by reference to the extent that it is
consistent herewith.
[0049] The article 20 can further comprise an absorbent body
structure, and the absorbent body can include an absorbent
composite 44 component. In general, the absorbent composite can
have a significant amount of stretchability and can include
absorbent material, such as superabsorbent material and/or fluff.
Additionally, the absorbent material can be operatively contained
within a matrix of fibers. Accordingly, the article can comprise a
stretchable absorbent composite 44 that includes a quantity of
superabsorbent material and/or fluff operatively contained within a
matrix of fibers. Additionally, the fibrous matrix can include an
operative amount of elastomeric polymer fibers.
[0050] The absorbent composite 44 may have any of a number of
shapes. For example, the absorbent composite 44 may be rectangular
shaped, triangular shaped, oval shaped, race-track shaped,
I-shaped, generally hourglass shaped, T-shaped, or the like. It is
often suitable for the absorbent composite 44 to be narrower in the
crotch portion 36 than the rear 34 or front 32 portion(s). The
absorbent composite 44 can be attached to an absorbent article by
bonding means known in the art, such as ultrasonic, pressure,
adhesive, heat, sewing thread or strand, autogenous or
self-adhering, hook-and-loop (for example where the elastomeric
polymer functions as the loop), or any combination thereof. For
example, a region of the absorbent composite 44 designed to exhibit
attachment properties may be bonded to the topsheet, the backsheet,
or both, of an absorbent article.
[0051] In particular aspects, the absorbent composite 44 can
include discrete regions which comprise varying amounts of
absorbent and/or elastomeric material. For example, the absorbent
composite 44 can have at least one first region and at least one
second region. In one particular feature, the first region
comprises at least one elastomeric polymer in a first concentration
and at least one superabsorbent material. For example, the first
region may comprise elastomeric polymer in a concentration of about
15-percent or less by weight in that region, and may further
comprise superabsorbent material in a concentration of about
40-percent or greater by weight in that region, such as about
65-percent or greater or about 85-percent or greater by weight. In
another example, the second region may comprise at least one
elastomeric polymer in a second concentration of about 30-percent
or greater by weight in that region, such as about 70-percent or
greater or at least about 90-percent or greater by weight. In a
particular aspect, the second concentration by weight of
elastomeric polymer is higher than the first.
[0052] In particular aspects, at least one of the regions of the
absorbent composite 44 may also include additional components as
well, including, but not limited to, natural fibers, synthetic
fibers, fluid modifiers, surfactants, and odor control additives.
In one example, the first region comprises about 35-percent or less
by weight natural fiber, such as about 25-percent or less, or
15-percent or less by weight.
[0053] Each region may further be characterized as having distinct
desirable properties as compared to other regions. In one example,
the first region may exhibit improved absorbent properties, such as
absorbent capacity. In another example, the second region may
exhibit improved attachment strength for attaching the absorbent
composite to an absorbent article, prior to and/or after fluid
insult. In other aspects, each region can provide additional or
alternative properties including, but not limited to, shape, size,
relative location, basis weight, intake rate, caliper, thickness,
density, permeability, and stretchability, as well as combinations
thereof. FIGS. 3A-3B demonstrate an example of an absorbent
composite with first and second regions which exhibit distinct
properties. FIG. 3A exhibits a plan view of an example absorbent
composite 44 of the present invention having two second regions 120
that could exhibit desired attachment strength properties. The
second regions are located on an edge portion of the absorbent
composite, with the remainder of the absorbent composite comprising
a first region 100. FIG. 3B exhibits a cross-section view of the
same example, demonstrating a unique caliper profile between the
first and second regions. It is a feature of the present invention
that the absorbent composite is not limited to merely two regions,
but rather may have any number of regions, each comprising a
desired set of properties.
[0054] The regions can be selectively located in any desired shape
and size within the absorbent composite. Typically, the first
region is intended primarily for absorbing fluids and is located in
at least an area intended to be in close proximity to the discharge
orifice of the user. The second region is intended primarily for
attachment purposes and is typically located in areas where
attachment is desired.
[0055] FIGS. 4A-4G display several non-limiting examples of various
arrangements which may be used in the present invention. FIG. 4A
demonstrates a rectangular shaped example absorbent composite 44 of
the present invention having two second regions 120, each located
on an edge portion of the absorbent composite and each being
continuous from one distal end portion to the opposing distal end
portion of the composite, with the remainder of the absorbent
composite comprising a first region 100. FIG. 4B demonstrates an
hour-glass shaped example absorbent composite 44 of the present
invention having four second regions 120, each located on an edge
portion of the absorbent composite, with the remainder of the
absorbent composite comprising a first region 100. FIG. 4C
demonstrates an I-shaped example absorbent composite 44 of the
present invention having two second regions 120, each located on a
transverse edge portion of the absorbent composite, with the
remainder of the absorbent composite comprising a first region 100.
FIG. 4D demonstrates a race-track shaped example absorbent
composite 44 of the present invention having four second regions
120, each situated diagonally in a corner portion of the absorbent
composite, with the remainder of the absorbent composite comprising
a first region 100. FIG. 4E demonstrates a rectangular example
absorbent composite 44 of the present invention having numerous
second regions 120 and third regions 130, organized in a
"zebra-type" pattern in the absorbent composite, with the remainder
of the absorbent composite comprising a first region 100. FIG. 4F
demonstrates a rectangular shaped example absorbent composite 44 of
the present invention having one continuous second region 120,
comprising nearly 50-percent of the total area of the absorbent
composite, and numerous first regions 100. FIG. 4G demonstrates a
triangular shaped example absorbent composite 44 of the present
invention having three second regions 120 and two first regions
100. Additionally, regions can be placed randomly within an
absorbent composite (not shown) as opposed to the patterns
displayed in the figures. Also each region can differ in shape from
others, such as circular, diamond-shaped, hexagonal, star-shaped,
and the like.
[0056] Each region can account for a selected amount of the total
surface area of the absorbent composite. For example, if one type
of region is designed to have desired properties, such as
attachment strength, the sum of the regions of that type may have a
total surface area which accounts for about 50-percent or less,
such as about 30-percent or less, of the total surface area of the
absorbent composite. In another example, a particular type of
region may have other desired properties, such as absorbency
capacity, which may have a total surface area that accounts for
about 50-percent or more, such as about 70-percent or more of the
total surface area of the absorbent composite.
[0057] The absorbent composite of the present invention can
additionally comprise at least one "target zone," as defined above.
At least a portion of any of the regions may be located in the
target zone. For example, in one aspect, at least a portion of the
first region is located in the target zone. The target zone may
suitably comprise the entire length of an absorbent composite or
may comprise a specific area as desired. For example, the target
zone may comprise at least about 25-percent of the area of the
absorbent composite, such as at least about 50-percent or at least
about 75-percent of the area.
[0058] The amount of superabsorbent material in the absorbent
composite can be at least about 40-percent by weight of the
composite, such as at least about 65-percent or at least about
75-percent by weight of the composite to provide improved benefits.
Optionally, the amount of superabsorbent material can be at least
about 95-percent by weight of the composite.
[0059] The absorbent components can have corresponding
configurations of absorbent capacities, configurations of
densities, configurations of basis weights and/or configurations of
sizes which are selectively constructed and arranged to provide
desired combinations of liquid intake time, absorbent saturation
capacity, absorbent retention capacity, liquid distribution along
the thickness and x-y directions of the article, shape maintenance,
and aesthetics.
[0060] The absorbent composite or its selected regions can have a
selected density, as determined under a confining pressure of 0.2
psi (1.38 KPa). In a particular feature, the absorbent composite
density can be at least a minimum of about 0.1 grams per cubic
centimeter (g/cm.sup.3). The density of the absorbent composite can
alternatively be at least about 0.25 g/cm.sup.3, and can optionally
be at least about 0.3 g/cm.sup.3. In another feature, the density
of the high superabsorbent containing first region of the absorbent
composite can be up to about 0.4 g/cm.sup.3. A higher density can
be helpful to increase the superabsorbent containment within the
absorbent composite. Desired configurations of the stretchable
absorbent composite can have a density within the range of about
0.20 to 0.35 g/cm.sup.3. The densities of the two regions may be
different, where the second region with higher amount of
elastomeric polymer may have a density higher than 0.4
g/cm.sup.3.
[0061] The absorbent composite or its selected regions can have any
desirable basis weight. In a particular feature, the absorbent
composite has a basis weight of at least about 200 grams per square
meter (gsm). In another feature, the basis weight of the absorbent
composite is at least 800 gsm. The basis weights of the first
region can be different from the second region.
[0062] The superabsorbent material can be selected from natural,
synthetic and modified natural polymers and materials. The
superabsorbent material can be inorganic materials, such as silica
gels, or organic compounds, such as crosslinked polymers. The term
"crosslinked" refers to any means for effectively rendering
normally water-soluble materials substantially water insoluble, but
swellable. Such means can comprise, for example, physical
entanglement, crystalline domains, covalent bonds, ionic complexes
and associations, hydrophilic associations, such as hydrogen
bonding, and hydrophobic associations or Van der Waals forces.
[0063] Examples of synthetic, polymeric, superabsorbent materials
include the alkali metal and ammonium salts of poly(acrylic acid)
and poly(methacrylic acid), poly(acrylamides), poly(vinyl ethers),
maleic anhydride copolymers with vinyl ethers and alpha-olefins,
poly(vinyl pyrolidone), poly(vinyl morpholinone), poly(vinyl
alcohol), and mixtures and copolymers thereof. Further polymers
suitable for use in the absorbent composite include natural and
modified natural polymers, such as hydrolyzed acrylonitrile-grafted
starch, acrylic acid grafted starch, methyl cellulose,
carboxymethyl cellulose, hydroxypropyl cellulose, and the natural
gums, such as alginates, xanthum gum, locust bean gum, and the
like. Mixtures of natural and wholly or partially synthetic
absorbent polymers can also be useful. Processes for preparing
synthetic, absorbent gelling polymers are disclosed in U.S. Pat.
No. 4,076,663, issued to Masuda et al., and U.S. Pat. No.
4,286,082, issued to Tsubakimoto et al., all of which are
incorporated herein by reference to the extent that they are
consistent herewith.
[0064] The superabsorbent material may be in a variety of geometric
forms. In one example, the superabsorbent material is in the form
of discrete particles. However, the superabsorbent material may
also be in the form of fibers, flakes, rods, spheres, needles,
particles coated with fibers or other additives, films, and the
like.
[0065] Superabsorbent materials suitable for use in the present
invention are known to those skilled in the art. Generally stated,
the superabsorbent material can be a water-swellable, generally
water-insoluble, hydrogel-forming polymeric absorbent material,
which is capable, under the most favorable conditions, of absorbing
at least about 10 times its weight, or at least about 15 times its
weight, or at least about 25 times its weight in an aqueous
solution containing 0.9 weight percent sodium chloride. The
hydrogel-forming polymeric absorbent material may be formed from
organic hydrogel-forming polymeric material, which may include
natural material such as agar, pectin, and guar gum; modified
natural materials such as carboxymethyl cellulose, carboxyethyl
cellulose, chitosan salt, and hydroxypropyl cellulose, and
synthetic hydrogel-forming polymers. Synthetic hydrogel-forming
polymers include, for example, alkali metal salts of polyacrylic
acid, polyacrylamides, polyvinyl alcohol, ethylene maleic anhydride
copolymers, polyvinyl ethers, polyvinyl morpholinone, polymers and
copolymers of vinyl sulfonic acid, polyacrylates, polyvinyl amines,
polyquaternary ammonium, polyacrylamides, polyvinyl pyridine, and
the like. Other suitable hydrogel-forming polymers include
hydrolyzed acrylonitrile grafted starch, acrylic acid grafted
starch, and isobutylene maleic anhydride copolymers and mixtures
thereof. The hydrogel-forming polymers are desirably lightly
crosslinked to render the material substantially water insoluble.
Crosslinking may, for example, be by irradiation or covalent,
ionic, Van der Waals, or hydrogen bonding. Suitable base
superabsorbent materials are available from various commercial
vendors, such as Stockhausen, Inc., BASF Inc. and others. In one
example, the superabsorbent material was FAVOR SXM 9394, available
from Stockhausen, Inc., a business having offices located in
Greensboro, N.C., U.S.A. The superabsorbent material may desirably
be included in an appointed storage or retention portion of the
absorbent system, and may optionally be employed in other
components or portions of the absorbent article. In one feature,
the superabsorbent material can be selectively positioned within
the composite such that the absorbent composite comprises regions
of varying superabsorbent material concentration. Superabsorbent
materials can be incorporated into the absorbent composite
externally or by in-situ polymerization.
[0066] The absorbent composite 44 of the present invention can
include operative concentrations of elastomeric polymer which can
vary among selected regions. For example, some regions may be
designed to have enhanced fluid absorbency, while other regions may
be designed for enhanced attachment strength of the absorbent
composite to an absorbent article. For example, the first region
may be designed to have high absorbent capacity and the second
region may be designed to have high attachment strength. In one
particular aspect, the amount of elastomeric polymer fibers in the
first region is about 15-percent or less, based on the total weight
of the absorbent composite in that region, and the amount of
elastomeric polymer fibers in the second region is at least about
40-percent, based on the total weight of the absorbent composite in
that region. In another particular aspect, the amount of
elastomeric polymer fibers in the first region is about 40-percent
or less, such as about 25-percent or less based on the total weight
of the absorbent composite in that region. In yet another
particular aspect, the amount of elastomeric polymer fibers in the
second region is at least about 70-percent or greater, such as
about 90-percent or greater based on the total weight of the
absorbent composite in that region.
[0067] If the amount of elastomeric polymer in each region of the
absorbent composite is outside the desired values, various
disadvantages can occur. For example, an insufficient amount of
elastomeric polymer may provide an inadequate level of structural
integrity, and an inadequate ability to stretch and retract
elastomerically. An excessively high amount of elastomeric polymer
in a region intended for absorption may hold superabsorbent
material too tightly and may not allow a sufficient amount of
swelling. In this scenario, the restricted swelling of the
superabsorbent material can excessively limit the absorbent
capacity of the composite. Where the elastomeric polymer is
generally hydrophobic, an excessively large amount of elastomeric
polymer in a region intended for absorption may undesirably limit
the intake rate at which the composite acquires fluid, and may
limit the distribution of fluid to other parts of the absorbent
composite. Furthermore, an excessive amount of elastomeric polymer
may hinder the ability of the absorbent composite to stretch in
that region. Alternatively, an insufficient amount of elastomeric
fibers in a region which is designed for attachment may result in
detachment of the composite from the article during use due to
swelling and/or stretching of the absorbent materials, which in
turn can result in poor fit and discomfort.
[0068] The elastomeric material of the polymer fibers may include
an olefin elastomer or a non-olefin elastomer, as desired. For
example, the elastomeric fibers can include olefinic copolymers,
polyethylene elastomers, polypropylene elastomers, polyester
elastomers, polyisoprene, cross-linked polybutadiene, diblock,
triblock, tetrablock, or other multi-block thermoplastic
elastomeric and/or flexible copolymers such as block copolymers
including hydrogenated butadiene-isoprene-butadiene block
copolymers; stereoblock polypropylenes; graft copolymers, including
ethylene-propylene-diene terpolymer or ethylene-propylene-diene
monomer (EPDM) rubber, ethylene-propylene random copolymers (EPM),
ethylene propylene rubbers (EPR), ethylene vinyl acetate (EVA), and
ethylene-methyl acrylate (EMA); and styrenic block copolymers
including diblock and triblock copolymers such as
styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS),
styrene-isoprene-butadiene-styrene (SIBS),
styrene-ethylene/butylene-styrene (SEBS), or
styrene-ethylene/propylene-styrene (SEPS), which may be obtained
from Kraton Inc., a business having offices located in Houston,
Tex. U.S.A. under the trade designation KRATON elastomeric resin or
from Dexco, a division of ExxonMobil Chemical Company, a business
having offices located in Houston, Tex. U.S.A. under the trade
designation VECTOR (SIS and SBS polymers); blends of thermoplastic
elastomers with dynamic vulcanized elastomer-thermoplastic blends;
thermoplastic polyether ester elastomers; ionomeric thermoplastic
elastomers; thermoplastic elastic polyurethanes, including those
available from E. I. Du Pont de Nemours Co., a business having
offices located in Wilmington, Del. U.S.A. under the trade name
LYCRA polyurethane, and ESTANE available from Noveon, Inc., a
business having offices located in Cleveland, Ohio U.S.A;
thermoplastic elastic polyamides, including polyether block amides
available from AtoFina Chemicals, Inc., a business having offices
located in Philadelphia, Pa. U.S.A. under the trade name PEBAX;
polyether block amide; thermoplastic elastic polyesters, including
those available from E. I. Du Pont de Nemours Co., under the trade
name HYTREL, and ARNITEL from DSM Engineering Plastics, a business
having offices located in Evansville, Ind., U.S.A. and single-site
or metallocene-catalyzed polyolefins having a density of less than
about 0.89 grams/cubic centimeter, available from Dow Chemical Co.,
a business having offices located in Freeport, Tex. U.S.A. under
the trade name AFFINITY; and combinations thereof.
[0069] As used herein, a tri-block copolymer has an ABA structure
where the A represents several repeat units of type A, and B
represents several repeat units of type B. As mentioned above,
several examples of styrenic block copolymers are SBS, SIS, SIBS,
SEBS, and SEPS. In these copolymers the A blocks are polystyrene
and the B blocks are a rubbery component. Generally these triblock
copolymers have molecular weights that can vary from the low
thousands to hundreds of thousands and the styrene content can
range from 5-percent to 75-percent based on the weight of the
triblock copolymer. A diblock copolymer is similar to the triblock
but is of an AB structure. Suitable diblocks include
styrene-isoprene diblocks, which have a molecular weight of
approximately one-half of the triblock molecular weight having the
same ratio of A blocks to B blocks.
[0070] In desired arrangements, the polymer fibers can include at
least one material selected from the group consisting of styrenic
block copolymers, elastic polyolefin polymers and co-polymers and
EVA/AMA type polymers.
[0071] In particular arrangements, for example, the elastomeric
material of the polymer fibers can include various commercial
grades of low crystallinity, lower molecular weight metallocene
polyolefins, available from ExxonMobil Chemical Company, a company
having offices located in Houston, Tex., U.S.A. under the VISTAMAXX
trade designation. The VISTAMAXX material is believed to be
metallocene propylene ethylene co-polymer. In one example, the
elastomeric polymer was VISTAMAXX PLTD 1778. In another example,
the elastomeric polymer was VISTAMAXX PLTD 2210. Another optional
elastomeric polymer is KRATON blend G 2755 from Kraton Inc., a
company having offices located in Houston, Tex., U.S.A. The KRATON
material is believed to be a blend of styrene ethylene-butylene
styrene polymer, ethylene waxes and tackifying resins.
[0072] In another feature, the polymer fibers include an operative
amount of a surfactant. The surfactant can be combined with the
polymer fibers in any operative manner. Various techniques for
combining the surfactant are conventional and well known to persons
skilled in the art. For example, the surfactant may be compounded
with the polymer employed to form the meltblown fibers. In a
particular feature, the surfactant may be configured to operatively
migrate or segregate to the outer surface of the fibers upon the
cooling of the fibers. Alternatively, the surfactant may be applied
to or otherwise combined with the polymer fibers after the fibers
have been formed.
[0073] The polymer fibers include an operative amount of a
surfactant, based on the total weight of the fibers and surfactant.
In particular aspects, the polymer fibers can include at least a
minimum of about 0.1-percent by weight surfactant, as determined by
water extraction. The amount of surfactant can alternatively be at
least about 0.15-percent by weight, and can optionally be at least
about 0.2-percent by weight to provide desired benefits. In other
aspects, the amount of surfactant can be generally not more than a
maximum of about 2-percent by weight, such as not more than about
1-percent by weight, or not more than about 0.5-percent by weight
to provide improved performance.
[0074] If the amount of surfactant is outside the desired ranges,
various disadvantages can occur. For example, an excessively low
amount of surfactant may not allow the hydrophobic meltblown fibers
to wet with the absorbed fluid. An excessively high amount of
surfactant may allow the surfactant to wash off from the fibers and
undesirably interfere with the ability of the composite to
transport fluid, or may adversely affect the attachment strength of
the absorbent composite to an absorbent article. Where the
surfactant is compounded or otherwise internally added to the
elastomeric polymer, an excessively high level of surfactant can
create conditions that cause a poor formation of the polymer
fibers.
[0075] In desired configurations, the surfactant can include at
least one material selected from the group that includes
polyethylene glycol ester condensates and alkyl glycoside
surfactants. For example, the surfactant can be a GLUCOPON
surfactant, available from Cognis Corporation, a business having
offices located in Cincinnati, Ohio, U.S.A, which can be composed
of 40-percent water, and 60-percent d-glucose, decyl, octyl ethers
and oligomerics.
[0076] A particular example of a sprayed-on surfactant can include
a water/surfactant solution which includes 16 liters of hot water
(about 45.degree. C. to 50.degree. C.) mixed with 0.20 kg of
GLUCOPON 220 UP surfactant and 0.36 kg of ALCHOVEL Base N-62
surfactant. This is a 1:3 ratio of the GLUCOPON 220 UP surfactant
to the ALCHOVEL Base N-62 surfactant. GLUCOPON 220 UP is available
from Cognis Corporation, a business having offices located in
Cincinnati, Ohio, U.S.A. ALCHOVEL Base-N62 is available from
Uniqema, a business having offices located in New Castle, Del.,
U.S.A. When employing a sprayed-on surfactant, a relatively lower
amount of sprayed-on surfactant may be desirable to provide the
desired containment of the superabsorbent material. Excessive
amounts of the fluid surfactant may hinder the desired attachment
of the superabsorbent material to the molten, elastomeric meltblown
fibers.
[0077] An example of an internal surfactant or wetting agent that
can be compounded with the elastomeric fiber polymer can include a
MAPEG DO 400 PEG (polyethylene glycol) ester. This material is
available from BASF, a business having offices located in Freeport,
Tex., U.S.A. Other internal surfactants can include a polyether, a
fatty acid ester, a soap or the like, as well as combinations
thereof.
[0078] In a particular feature, an operative amount of the polymer
fibers can have a fiber diameter of not less than about 8 microns
(.mu.m). Another feature can have a configuration in which an
operative amount of the polymer fibers have a fiber diameter of not
more than about 20 .mu.m. In a further feature, not more than
20-percent by weight, such as not more than about 15-percent by
weight of the meltblown, elastomeric polymer fibers in the
absorbent composite 44 have a fiber diameter of less than 8 .mu.m.
Still another feature can have a configuration in which not more
than about 20-percent by weight, such as not more than about
15-percent by weight of the elastomeric polymer fibers have a fiber
diameter greater than about 20 .mu.m.
[0079] If the amount or proportion of the small polymer fibers
(fiber diameter less than about 8 .mu.m) is too great, the
absorbent composite 44 may exhibit inadequate levels of
stretchability. An overly great amount of the small polymer fibers
in a region intended for absorption may also excessively constrain
the superabsorbent material and not allow a desired amount of
swelling in the superabsorbent material. Additionally, the smaller
fibers can become stress crystallized, and the tensions (modulus)
of the stretchable composite 44 can be too high.
[0080] If the amount or proportion of large polymer fibers (fiber
diameter greater than about 20 .mu.m) is too great, the absorbent
composite 44 may exhibit inadequate levels of material containment.
The meltblown elastomeric fibers may not provide a sufficient
amount of fiber surface area, and the superabsorbent material may
not be adequately contained and held in the matrix of elastomeric
polymer fibers.
[0081] In another feature, the elastomeric polymer fibers can be
produced from a polymer material having a selected melt flow rate
(MFR). In a particular aspect, the MFR can be up to a maximum of
about 300. Alternatively, the MFR can be up to about 230 or 250. In
another aspect, the MFR can be a minimum of not less than about 20.
The MFR can alternatively be not less than about 50 to provide
desired performance. The described melt flow rate has the units of
grams flow per 10 minutes (g/10 min). The parameter of melt flow
rate is well known and can be determined by conventional
techniques, such as by employing test ASTM D 1238 70 "extrusion
plastometer" Standard Condition "L" 230.degree. C. and 2.16 kg
applied force.
[0082] In conventional absorbent articles, absorbent composites
often detach from the article, particularly as the concentration of
absorbent materials, such as superabsorbent materials, increases
(such as greater than 30-percent by weight) or after fluid insult.
For example, when exposed to a fluid insult, superabsorbent
material tends to swell and change from a hard, solid material to a
soft, gel-like material which can result in breaking or weakening
of at least some of the bonds which adhere the absorbent composite
to an absorbent article. Other issues such as pad cracking, pad
bunching or twisting often occur due to detachment from the outer
cover 40 and/or liner 42. For absorbent articles with coform
absorbent composites, detachment from the outer cover 40 and/or
liner 42 after fluid insult often cause the absorbent composite to
fold over itself. To overcome the difficulties of the prior
arrangements, the present invention can be configured to
incorporate one or more of the aspects and features set forth in
the present disclosure. In a particular feature, regions of varying
elastomeric polymer concentrations are selectively configured
within the absorbent composite. In general, a greater concentration
of elastomeric polymer in a particular region of an absorbent
composite which is attached to the other component of the article
will result in stronger attachment strength between the composite
and an absorbent article before and/or after a fluid insult. For an
absorbent article that is stretchable in at least one direction and
which utilizes an absorbent composite that is also stretchable,
good attachment between the composite and the article may allow for
the maximum utilization of the stretch provided by the composite,
resulting in better fit and comfort.
[0083] The absorbent composite 44 can further include a definite,
discrete amount of hydrophilic fibers, such as cellulose or
cellulosic fibers. These fibers, if any, can be mixed with any
superabsorbent material which may be present. In a particular
version, the absorbent composite 44 comprises a mixture of
superabsorbent hydrogel-forming material and wood pulp fluff. The
wood pulp fluff may be exchanged with other natural fibers,
synthetic fibers, meltblown fibers or with a combination thereof.
The superabsorbent material may be substantially homogeneously
mixed with the hydrophilic fibers or may be non-uniformly
mixed.
[0084] The amount of hydrophilic fibers may be in an amount of
0-percent or greater, and in particular configurations of the
invention, can be about 5-percent or greater based upon the total
weight of the elastomeric absorbent composite in the region. In
another aspect, the amount of cellulosic or other hydrophilic
fibers can be about 35-percent or less, such as about 25-percent or
less, or about 15-percent or less, based upon the total weight of
the elastomeric absorbent composite in the region.
[0085] The selected amounts of cellulosic or other hydrophilic
fiber can help provide increased levels of fluid intake and
wicking. Excessive amounts of hydrophilic fibers, however, can
undesirably increase the caliper of the composite and may limit
properties such as elasticity, stretch and recovery. Additionally,
overly large amounts of the hydrophilic fiber can lead to excessive
cracking of the absorbent composite during extension and
stretching.
[0086] The cellulosic fibers may include, but are not limited to,
chemical wood pulps such as sulfite and sulfate (sometimes called
Kraft) pulps, as well as mechanical pulps such as ground wood,
thermomechanical pulp and chemithermomechanical pulp. More
particularly, the pulp fibers may include cotton, typical wood
pulps, cellulose acetate, rayon, thermomechanical wood pulp,
chemical wood pulp, debonded chemical wood pulp, milkweed floss,
and combinations thereof. Pulps derived from both deciduous and
coniferous trees can be used. Additionally, the cellulosic fibers
may include such hydrophilic materials as natural plant fibers,
cotton fibers, microcrystalline cellulose, microfibrillated
cellulose, or any of these materials in combination with wood pulp
fibers. Suitable cellulosic fibers can, for example, include NB
416, a bleached southern softwood Kraft pulp, available from
Weyerhaeuser Co., a business having offices located in Federal Way,
Wash. U.S.A.; CR 54, a bleached southern softwood Kraft pulp,
available from Bowater Inc., a business having offices located in
Greenville, S.C. U.S.A.; SULPHATATE HJ, a chemically modified
hardwood pulp, available from Rayonier Inc., a business having
offices located in Jesup, Ga. U.S.A.; NF 405, a chemically treated
bleached southern softwood Kraft pulp, available from Weyerhaeuser
Co.; and CR 1654, a mixed bleached southern softwood and hardwood
Kraft pulp, available from Bowater Inc. Desired configurations of
the absorbent composites of the invention can, for example, include
a pulp fiber content which is in the range of 0-percent to about
35-percent. In one particular aspect, the first region contains
about 35-percent or less CR 1654 pulp. In another particular
aspect, the first region contains about 35-percent or less NB 416
pulp.
[0087] In a particular aspect, the absorbent composite has at least
a first region which comprises about 60-percent by weight in that
region or greater superabsorbent material, about 35-percent by
weight in that region hydrophilic fibers or less, and about
15-percent by weight in that region elastomeric polymer or less,
and at least one second region which comprises about 80-percent by
weight in that region elastomeric polymer or greater. The second
region of this particular aspect may additionally be in the form of
rectangular strips which run along at least two opposing edges of
the absorbent composite.
[0088] The absorbent composite of the present invention can be
extensible, and/or elastomerically extensible at least about
30-percent, such as at least about 50-percent, or at least about
75-percent, based on length in an unstretched condition.
Alternatively, the absorbent composite of the present invention can
be extensible, and/or elastomerically extensible at about
200-percent or less, such as about 100-percent or less based on
length in an unstretched condition to provide desired
effectiveness.
[0089] If the stretchability parameter is outside the desired
values, the absorbent composite may not be sufficiently flexible to
provide desired levels of fit and conformance to the shape of the
user. A donning of a product that includes such an absorbent
composite would then be more difficult. For example, training pant
products may be accidentally stretched to large amounts before use,
and the absorbent system may rip and tear. As a result, the
absorbent composite may exhibit excessive leakage problems.
[0090] Another feature of the invention can include regions in
which superabsorbent material has been combined with elastomeric
polymer during formation of the absorbent composite in a
meltblowing operation. Where the absorbent composite 44 includes
cellulosic fibers, the superabsorbent material can be operatively
mixed with the cellulosic fibers, and the mixture can then be
operatively combined with the meltblown polymer fibers.
[0091] Techniques and systems for producing nonwoven fibrous webs
which include meltblown fibers are well known in the art. For
example, a suitable technique is disclosed in U.S. Pat. No.
4,100,324 to R. A. Anderson. Other suitable techniques are
described in U.S. Pat. No. 5,350,624 to W. A. Georger, and U.S.
Pat. No. 5,508,102 to W. A. Georger. Absorbent, elastomeric
meltblown webs containing high amounts of superabsorbent are
described in U.S. Pat. No. 6,362,389 to D. J. McDowall, and
absorbent, elastomeric meltblown webs containing high amounts of
superabsorbent and low superabsorbent shake-out values are
described in pending U.S. patent application Ser. No. 10/883,174 to
X. Zhang et al. The entire disclosures of these documents are
incorporated herein by reference in a manner that is consistent
herewith. The meltblowing techniques can be readily adjusted in
accordance with conventional know-how to provide turbulent flows
that can operatively mix the selected fibers and superabsorbent
material. In a desired arrangement, the superabsorbent material and
selected fibers can be substantially homogeneously mixed during the
process of forming a web of the absorbent composite. The techniques
can also be readily adjusted in accordance with conventional
knowledge to provide the desired weight percentages of the selected
fibers and superabsorbent materials.
[0092] With reference to FIG. 5, a meltblowing process and
apparatus for forming a stretchable, absorbent composite web 51 of
the invention can have an appointed machine-direction 74 which
extends longitudinally along the processing sequence of the process
and apparatus, and an appointed lateral cross-deckle direction 70
which extends transversely. For the purposes of the present
disclosure, the machine-direction is the direction along which a
particular component or material is transported length-wise along
and through a particular, local position of the apparatus and
process. The cross-deckle direction 70 can lie generally within the
plane of the material being transported through the method and
apparatus, and is aligned perpendicular to the local
machine-direction. Accordingly, with reference to the arrangement
representatively shown in FIG. 5, the machine-direction 74 extends
perpendicular to the plane of the sheet of the drawing. As
representatively shown, the process and apparatus can include a
conventional fiberizer 54 which, if desired, provides a particular
amount of cellulosic fibers; an operative supply 56 of
superabsorbent material; and a delivery chute 58 which directs the
superabsorbent material and cellulosic fibers, if any, into the
cooperating portions of the forming process. The superabsorbent
supply system 56 can include any conventional metering device for
providing a desired flow rate of superabsorbent material into the
process. The forming process can further include a system of
meltblowing dies 60 which provide the desired elastomeric polymer
fibers, and a foraminous forming surface 52 on which a composite
web can be formed. As seen in FIGS. 6 and 7, the meltblowing die 60
positions can be staggered, and/or the horizontal angles can be
manipulated to provide desired regions of elastomeric polymer
concentrations within the absorbent composite. The forming surface
can, for example, be provided by a forming belt or by the generally
cylindrical, peripheral surface of a rotatable forming drum. With
reference to FIG. 5, the composite web 51 can be formed in a
substantially continuous operation, and the web can include the
superabsorbent material operatively held and contained in the
matrix of elastomeric polymer fibers, as well as any incorporated
cellulosic fibers.
[0093] In particular configurations, selected processing parameters
can be appropriately controlled to produce desired characteristics
in the absorbent composite of the present invention. For
example:
[0094] Melt-temperature--Higher melt-temperatures can provide
better containment of the incorporated superabsorbent material
(i.e., less shake-out). The elastomeric polymer can stay molten
longer, thereby increasing the chance that the material will hit
and attach to molten/softened polymer.
[0095] Die-to-Die Width--This parameter is the distance 64
representatively shown in FIG. 5. A smaller die-to-die width 64 can
give higher containment of the incorporated material. The meltblown
polymer fibers travel a smaller distance before contacting the
superabsorbent material, and can more readily connect to and be
captured by the still soft and sticky polymer material. The
die-to-die width distance 64 can, for example, be within the range
of about 4.5-10 inches. In one example, the die-to-die width is
about 9 inches. In another example, the die-to-die width is about
5.5 inches. The dies 60 can also be off-centered and staggered, in
relation to the center line of the duct 58 and each other, to
provide regions containing varying concentrations of absorbent
components and elastomeric polymer. In one example, the dies were
staggered 3 inches off center.
[0096] Relative Humidity--Lower relative humidity can provide a
higher containment of the incorporated superabsorbent material.
Ambient, fluid moisture can hinder the attachment between the
material and the polymer fibers. The superabsorbent material may
preferentially attach to the fluid instead of the polymer.
[0097] External Wetting Agent--Lower amounts of externally-applied
(e.g. sprayed-on) wetting agent can provide a higher containment of
superabsorbent material within the fiber matrix. A wetting agent
can hinder the attachment between the superabsorbent material and
the polymer fibers. The superabsorbent material may preferentially
attach to the fluid instead of the polymer.
[0098] Vacuum--This parameter is the vacuum level (e.g. measured in
inches of water) that is generated under the foraminous forming
surface 52 and the composite web 51 during the web forming
operation. A higher vacuum can provide a higher containment of
superabsorbent material. The higher vacuum can help provide a
tighter, more locked-together structure.
[0099] Fiber Diameter/Primary air pressure--This parameter is the
air pressure of the forming gas (e.g. air) that is generated close
to the exit of the air channels that are typically incorporated at
the tip of the meltblowing die 60. The primary air pressure can,
for example be expressed in the units of "psig" (pounds per square
inch--gauge). For example, a selected exit air velocity, typically
in the range of 0.4-1.0 Mach, can be provided at the air exit,
depending on the primary air pressure and the air gap spacing
employed within the meltblowing die. The air gap spacing is
measured from a knife edge of the meltblowing die tip to an inside
edge of the air plate in the meltblowing die. In a typical
arrangement, the air gap spacing can be within the range of about
0.015-0.084 inches. A higher, primary-air velocity can create
smaller fibers and help provide a higher containment of the
material. The smaller fibers can provide an increased amount of
surface area to which the material can attach. The smaller fibers
are also more flexible and can more readily entangle around a
superabsorbent material, such as a particle.
[0100] Die angle--This parameter is the angle 66 representatively
shown in FIG. 5. A large angle from the horizontal can reduce
contact between the polymer fibers and the material. The reduced
contact can decrease the containment of the material in the
composite, and can also create a non-homogenous (layered) sheet
which can degrade the containment of the superabsorbent material.
The die angle 66 can, for example, be within the range of about
35.degree.-80.degree. from horizontal. In a particular arrangement,
the die angle is about 57.degree. from horizontal. In another
arrangement, the die angle is about 70.degree..
[0101] Forming Height (Die-to-table)--This parameter is the
distance 62 between the meltblowing die 60 and the forming surface
52. A lower forming height can provide a higher containment of
material. Fiber entanglements can form more quickly and can help
hold and secure the material in the composite web. The forming
height 62 can, for example, be within the range of about 10-18
inches. In one example, the forming height is about 16 inches. In
another example, the forming height is about 12.75 inches. In still
another example, the forming height is about 11.5 inches.
[0102] Chute Height (Chute to table)--This parameter is the minimum
distance 68 between the exit of the delivery chute 58 and the
forming surface 52. A lower chute height 68 may give higher
containment of the superabsorbent material, as long as the material
sufficiently attached to the polymer fibers before hitting the
table. It is believed that the velocity of the superabsorbent
material can shoot it straight down the middle region of the system
of meltblowing dies employed to form the elastomeric polymer
fibers, and can quickly move the material into the molten polymer
when the fibers and material hit the table. The chute height 68
can, for example, be within the range of about 25.4-46 cm (about
10-18 inch). Particular arrangements of the process and apparatus
can include a chute height of about 41.3 cm (about 16.25 inch). The
chute may also be positioned at a particular angle from the machine
direction of the web, such as from 0.degree. to 50.degree. from the
MD direction. An angle of 0.degree. indicates that the chute is
parallel to the machine direction. In one example, the chute angle
was set at 20.degree. from the MD direction. In another example,
the chute angle was set at 45.degree. from the MD direction.
[0103] Additionally, the configuration of the process and apparatus
can provide a slant distance 50. Particular aspects of the process
and apparatus can be configured to provide a slant distance within
the range of about 4-6 inches (about 10-16.3 cm). In a particular
arrangement, the slant distance is about 5 inches (about 13 cm) to
provide desired benefits.
[0104] The process and apparatus can also be arranged to provide a
selected forming angle. In the various configurations of the
invention, the outlet opening of the delivery chute 58 can have a
short-axis and a long-axis. As representatively shown in FIG. 5,
the short axis can extend generally along the cross-deckle
direction 70 and the long-axis can extend generally perpendicular
to the plane of the drawing sheet. The chute angle is the angle
between the long-axis of the delivery chute and the local
machine-direction. A chute angle of zero degrees can, for example,
have the long-axis of the delivery chute 58 aligned along the
machine-direction of the process and apparatus. Additionally, the
long-axis can be approximately centered along the cross-deckle
direction 70 of the forming surface. A chute angle of 20 degrees
can have the long-axis of the delivery chute rotated 20 degrees
away from the local machine-direction at the center line position
of the delivery chute. The long-axis of the delivery chute can also
be substantially centered along the cross-deckle direction of the
forming surface. In particular aspects, the chute angle can be
within the range of about 0.degree.-90.degree.. One particular
arrangement of the process and apparatus includes a chute angle of
about 20.degree. to provide desired performance. The dies will
suitably be configured parallel to the chute exit. Therefore, the
entire forming system will be angled with the chute angle as
described above.
[0105] By incorporating its various features and configurations,
alone and in operative combinations, the invention can provide an
improved absorbent composite having a desired combination of
stretchability, absorbent capacity, particle-containment, and
attachment strength. The absorbent composite can be manufactured to
provide selected regions of absorbent component and/or elastomeric
polymer quantities. An absorbent article comprising the absorbent
composite of the present invention can be less susceptible to
premature leakage, and can provide improved comfort and fit,
improved protection and increased confidence to the wearer. For
example, the absorbent composite of the present invention, when in
an absorbent article, can help eliminate bunching, discomfort, and
worry by improving the attachment strength of the absorbent
composite to the absorbent article. Additional benefits can be
obtained if the absorbent composite of the present invention is
incorporated into a stretchable absorbent article.
[0106] The present invention is primarily described herein in
combination with an absorbent disposable training pant. It is
readily apparent to one skilled in the art based on the disclosure
herein, however, that the absorbent composite described herein can
also be used in combination with numerous other disposable
absorbent articles including, but not limited to, other personal
care absorbent articles, health/medical absorbent articles,
household/industrial absorbent articles, and the like.
Tests
Material Weight Test
[0107] A material weight test is used to measure the mass of a
die-cut material sample. The equipment necessary for this test
includes: [0108] A test facility having a temperature of 23.+-.6
degrees Celsius, and a relative humidity of 50.+-.10 percent.
[0109] A die stamp having a 3 inch (76.2 mm) diameter from MS
Laboratory Instruments, a business having offices located in
Fairport, N.Y. U.S.A. [0110] A suitable testing device is a METTLER
PE1600 electronic balance available from Mettler-Toledo AG, a
business having offices located in Greifensee, Switzerland, or an
equivalent device A sample is obtained by die cutting out the
material to be tested in the center of the web. The die cut
material sample is then placed on the balance and the mass of the
sample is recorded. Thickness/Density Test
[0111] A material thickness test is used to test the z-directional
thickness of the material composites. The thickness can be measured
in millimeters and then used to calculate density. The equipment
necessary for this test includes: [0112] A test facility having a
temperature of 23.+-.6 degrees Celsius, and a relative humidity of
50.+-.10 percent. [0113] A die stamp having a 3 inch (76.2 mm)
diameter from MS Laboratory Instruments, a business having offices
located in Fairport, N.Y. U.S.A. [0114] A SONY DIGITAL INDICATOR
gauge (available from Sony Precision Technology America Inc., a
business having offices located in Orange, Calif. U.S.A.), or an
equivalent device. [0115] A platen attached to the spindle of the
gauge having a 2 inch (50.8 mm) diameter that applies a force of
0.2 psi. A sample is obtained by die cutting out the material to be
tested. The die cut material sample is then placed between the
gauge and a surface or base plate. A suitable surface or base plate
should be level and should not flex as a result of the
platen/sample pressure. The sample is placed under the platen. The
platen is lowered onto the sample and full force is applied to the
sample for a duration of 3 seconds. The thickness is then
recorded.
[0116] The sample density is then calculated by the following
formula: Material Density = sample .times. .times. weight
.function. ( g ) ( sample .times. .times. area .function. ( cm 2 )
) * ( sample .times. .times. thickness .function. ( cm ) ) ##EQU1##
Dry Peel Test
[0117] A Dry Peel Test is used to test the effect of attachment
strength for the absorbent composite to an absorbent article. The
tensile force applied to peel apart a bond, such as an adhesive
bond or an ultra sonic bond, adjoining the two materials is
measured. The equipment necessary for this test includes: [0118] A
test facility having a temperature of 23.+-.6 degrees Celsius, and
a relative humidity of 50.+-.10 percent. [0119] A SINTECH constant
rate of extension tensile tester (available from MTS Systems
Corporation, a business having offices located in Eden Prairie,
Minn. U.S.A., or an equivalent device. [0120] Suitable software
(available from MTS Systems Corporation), or equivalent software.
[0121] Pneumatic-action grips having a 1 inch (25.4 mm) by 3 inch
(76.2 mm) grip face. [0122] A PAM gun, available from Fastening
Technologies, a business having offices loctated in Charlotte, N.C.
U.S.A. [0123] A BRANSON ultrasonic plunge bonder, model 920 from
Branson Ultrasonics Corporation, a business having offices located
in Danbury, Conn. U.S.A. The ultrasonic bonder should be equipped
with a plate horn having a bonding surface of 1 inch (2.54 cm) by 7
inches (17.78 cm). [0124] A 1 inch (25.4 mm) precision cutter
manufactured by Thwing Albert Instrument Company, a business having
offices located in Philadelphia, Pa. U.S.A. [0125] A 2 kg roller,
model number HR-100, available from KimInstruments, a business
having offices located in Fairfield, Ohio U.S.A.
[0126] Where a sample is prepared from a manufactured web (prior to
its incorporation into a product), samples should be obtained from
a segment of the web which has consistent and even formation. The
sample should be cut from the web in the orientation as would be
found in the finished product. Where the desired materials cannot
be obtained from a manufactured web, the sample may be extracted
from within the product. Care should be taken to maintain the
integrity of the bonds. The sample to be separated should be cut to
the desired dimensions. Where a given material or product will not
permit samples of the desired dimensions (for example, 1 inches
(2.54 cm) by 5 inches (12.7 cm)) to be prepared, the preferred
material dimensions selected should have a length that is at least
three times the width.
[0127] All samples should be tested at the same dimensions. Where
the width dimensions for a set of samples is under 2 inches (5.08
cm), at least 10 specimens of each sample should be tested, and
their results used in determining the average value for that
sample. Otherwise, five specimens should be tested and the results
averaged.
[0128] The procedure for samples having an adhesive bond is as
follows. The sample should be cut from a web to a size of 5 inches
(12.7 cm) by 10 inches (25.4 cm). A 19 mm wide swirl spray of
Bostik Findley H2525A adhesive, available from Bostik Findley,
Inc., a business having offices located in Wauwatosa, Wis. U.S.A.,
is applied to the sample using a PAM Gun. The PAM gun melter
temperature should be set to 312.degree. F. and the air pressure
should be set to 40 psi. The adhesive is applied to the center
length of the absorbent at about 0.1 gsm. A 5 inch (12.7 cm) by 10
inch (25.4 cm) 1.0 osy (33.5 g/m.sup.2) spunbond-meltblown-spunbond
(SMS) outer cover should then be positioned over the absorbent
composite sample and gently laid on top. A suitable SMS is used in
the current commercially available Exam Sheet, item number
67793-20, available from Kimberly-Clark Corporation, a business
having offices located in Neenah, Wis., U.S.A. A roller as
described above is then rolled over the bond area in two passes.
The sample is then cut into 1 inch (2.54 cm) wide.times.5 inch
length (12.7 cm) strips using a 1 inch (25.4 mm) precision cutter
manufactured by Thwing Albert Instrument Company, where the 5 inch
length is perpendicular to the adhesive line.
[0129] The procedure for samples having an ultrasonic bond is as
follows. The sample should be cut from a web to a size of 5 inches
(12.7 cm) by 10 inches (25.4 cm). A 5 inch (12.7 cm) by 10 inch
(25.4 cm) 1.0 osy (33.5 g/m.sup.2) spunbond-meltblown-spunbond
outer cover should be positioned over the absorbent sample and
gently laid on top. The composite is then ultrasonically bonded
using a BRANSON ultrasonic plunge bonder, as described above. The
composite is ultrasonically bonded along the length of the material
using 50 psi of pressure, with 0.2 seconds of weld time and 0.125
seconds of hold time. The anvil should have a single row of
rectangular dots pattern. Each rectangular dot should have a width
of 0.156 inches (0.397 cm) in the direction of the row and a length
of 0.125 inches (0.317 cm) by 0.125 inches (0.317 cm) in height.
Each rectangular dot should be spaced 0.375 inches (0.952 cm) from
the next one. After bonding, the sample is then cut into 1 inch
(2.54 cm) wide.times.5 inch (12.7 cm) length strips using a 1 inch
(25.4 mm) precision cutter manufactured by Thwing Albert Instrument
Company, as described above, such that each 5 inch length is
perpendicular to the bond rows and includes two bond points.
[0130] The samples (regardless of bond type) are then tested using
a SINTECH constant rate of extension tensile tester. The width of
the samples should be perpendicular to the direction of the tensile
force applied during the testing. The initial gage length (i.e. the
distance between the tensile tester jaws) is 50 mm. The bonded
sample is clamped in the jaws such that the bond is positioned
midway between the jaws. The outer cover tail should be clamped in
the upper jaw and the absorbent tail should be clamped in the lower
jaw. The moving jaw should travel at a constant rate of 250 mm/min.
The test is initiated and the sample is pulled until the bond is
broken or the material fractures. The peak load during peel is
recorded in grams.
Wet Peel Test
[0131] A Wet Peel Test is used to test the effect of attachment
strength after fluid insult for the absorbent composite to an
absorbent article. The tensile force applied to peel apart a bond,
such as an adhesive bond or an ultrasonic bond, adjoining the two
materials is measured.
[0132] The procedures used for both the Dry Peel Test and the Wet
Peel Test are substantially the same. However, the Wet Peel Test
further comprises the step of wetting the samples, which should
occur between the steps of bonding the samples and testing the
samples (using the SINTECH constant rate of extension tensile
tester) as described above in the Dry Peel Test. More particularly,
both adhesive and ultrasonic bonded samples that are designated for
wet peel testing are wetted in the following manner. The samples
should be soaked in 0.9-percent by weight sodium chloride solution,
(available from Ricca Chemical Company, a business having offices
located in Arlington, Tex. U.S.A.) such that the samples are
completely surrounded by solution for 20 minutes. The samples are
then placed on a 32 inch (81.3 cm).times.21 inch (53.3 cm) vacuum
box with the absorbent side facing the vacuum force. Solution is
then removed from the interstitial voids using a procedure similar
to that used in the SATCAP Test, as described in pending U.S.
patent application Ser. No. 10/820,636 filed on Apr. 8, 2004 by
Ranganathan et al. entitled "Differentially Expanding Absorbent
Structure." When on the vacuum box, an external pressure of 0.5 psi
should be applied to the samples for 5 minutes. The samples are
then removed from vacuum box and tested for tensile as described in
the Dry Peel Test above.
EXAMPLES
[0133] All examples were made using a coform process as described
above, utilizing a combination of two meltblown dies, a forming
drum, a superabsorbent material feeder, and a two-inch
fiberizer.
Example 1
[0134] This sample absorbent composite was configured to have a
first region with a relatively high concentration of superabsorbent
material and fluff and a relatively low concentration of
elastomeric polymer located approximately in the middle of the
absorbent composite, and two second regions with a relatively high
concentration of elastomeric polymer located on opposing edges. The
composite width (i.e., in the CD direction) was approximately 5.5
inches (13.0 cm). The width of the first region was approximately
4.5 inches (11.4 cm) and the width of each second region, which ran
continuously in the MD-direction of the absorbent composite, was
approximately 0.5 inches (1.3 cm). FIGS. 3A-3B illustrate an
exemplary plan view and cross-section profile of the sample. The
meltblown process settings were as described in Table I.
TABLE-US-00001 TABLE I Die Height 11.5 inches from highest point of
drum Die-to-Die distance 9 inches Die Staggering 3 inches off
center Die Angle 70.degree. from horizontal Both dies were parallel
to the pulp chute Chute Angle 20.degree. from horizontal Pulp
Nozzle Height 16 inches from highest point of drum Output Rate 0.47
grams/hole/minute
The resulting absorbent composite was produced having a nominal pad
weight of 17 grams and was comprised of 1.7 grams CR 1654 pulp,
2.55 grams PLTD 1778 elastomeric polymer, and 12.75 grams FAVOR SXM
9394 superabsorbent material. The resulting density of the first
region was 0.20 g/cc and the density of each second region was 0.17
g/cc.
Example 2
[0135] A second sample absorbent composite was configured to have a
first region with a relatively high concentration of superabsorbent
material and fluff and a relatively low concentration of
elastomeric polymer located approximately in the middle of the
absorbent composite, and two second regions with a relatively high
concentration of elastomeric polymer located on opposing edges. The
composite width (i.e., in the CD direction) was approximately 5.5
inches (13.0 cm). The width of the first region was approximately
4.5 inches (11.4 cm) and the width of each second region, which ran
continuously in the MD-direction of the absorbent composite, was
approximately 0.5 inches (1.3 cm). FIGS. 3A-3B illustrate an
exemplary plan view and cross-section profile of the sample. The
meltblown process settings were as described in Table II.
TABLE-US-00002 TABLE II Die Height 12.75 inches from highest point
of drum Die-to-Die distance 9 inches Die Staggering 3 inches off
center Die Angle 55.degree. from horizontal Both dies were parallel
to the pulp chute Chute Angle 20.degree. from horizontal Pulp
Nozzle Height 16 inches from highest point of drum Output Rate 0.46
grams/hole/minute
[0136] The resulting absorbent composite was produced having a
nominal pad weight of 17 grams and was comprised of 1.7 grams NB
416 pulp, 2.55 grams PLTD 1778 elastomeric polymer, and 12.75 grams
FAVOR SXM 9394 superabsorbent material. The resulting density of
the first region was 0.20 g/cc and the density of each second
region was 0.17 g/cc.
Examples 3-7
[0137] Examples 3-7 illustrate performance characteristics of
different regions that could be incorporated into the present
invention, based on the concentration of various components, such
as elastomeric polymer, superabsorbent material, and fluff. The
meltblown process settings for Examples 3-7 were as follows: the
die height was 13 inches from the highest point of the drum; the
die-to-die distance was 5.5 inches; the dies were not staggered;
the die angle was 57.degree. from horizontal; both dies were
parallel to the pulp chute; the chute angle was 45.degree. from
horizontal; the pulp nozzle height was 16 inches from the highest
point of the drum; and the output rate was 1 gram/hole/minute. The
components used in each sample were PLTD 2210 elastomeric polymer,
FAVOR SXM 9394 superabsorbent material (SAM), and NB 416 fluff
pulp. The composition and basis weight of each example can be
viewed in Table III below. TABLE-US-00003 TABLE III Polymer %
polymer basis Fluff basis SAM basis Total basis Example in % fluff
in % SAM in weight weight weight weight Number composite composite
composite (gsm) (gsm) (gsm) (gsm) 3 15 10.0 75.0 74 50 373 497 4 44
26.0 30.0 360 210 240 810 5 57 20.0 23.0 360 126 140 620 6 60 12.0
28.0 360 73 169 605 7 100 0.0 0.0 360 0 0 360
[0138] Each example was then measured for thickness and weight, and
density was then derived (as described above), as seen in Table IV
below. The examples were then tested for dry peel strength
according to the Dry Peel Test described above, and for wet peel
strength according to the Wet Peel Test described above. The
results can be seen in Table IV, which demonstrate, inter alia,
that as the concentration of elastomeric polymer increases, the dry
and wet attachment strengths (i.e., peel strengths) also increase.
TABLE-US-00004 TABLE IV Findley Findley Ultra Sonic H2525A Ultra
Sonic H2525A Dry Dry Wet Wet Example Thickness Weight Density Peak
Load Peak Load Peak Load Peak Load Number (cm) (g) (g/cc) (g) (g)
(g) (g) 3 0.21 2.09 0.21 73.67 59.53 5.00 48.63 4 0.57 4.10 0.16
458.83 166.73 509.00 70.33 5 0.33 2.64 0.17 640.13 250.87 791.60
115.10 6 0.35 2.90 0.18 737.57 302.90 812.20 260.25 7 0.13 1.62
0.28 929.53 815.30 885.53 826.27
[0139] Lastly, Table V below shows that the ratio of Examples 4-7
(which could each represent a second region) to Example 3 (which
could represent a first region) is greater than 1. This further
demonstrates that as the concentration of elastomeric polymer
increases, the dry and wet attachment strengths (i.e., peel
strengths) also increase. For instance, composites of the present
invention have a suitable second region to first region dry peel
strength ratio of 1 or greater, such as about 5 or greater,
depending upon the type of bonding that is utilized. Likewise,
composites of the present invention have a suitable second region
to first region wet peel strength ratio of 1 or greater, such as
about 100 or greater, depending upon the type of bonding that is
utilized. Composites having ratios as those described above provide
improved attachment strength, as well as suitable absorbent
properties. TABLE-US-00005 TABLE V Findley Findley 2.sup.nd Region/
Ultra Sonic H2525A Ultra Sonic H2525A 1.sup.st Region Dry Peel Dry
Peel Wet Peel Wet Peel Ratio Ratio Ratio Ratio Ratio 4:3 6.23 2.80
101.80 1.45 5:3 8.69 4.21 158.32 2.37 6:3 10.01 5.09 162.44 5.35
7:3 12.62 13.69 177.11 16.99
[0140] It will be appreciated that details of the foregoing
examples, given for purposes of illustration, are not to be
construed as limiting the scope of this invention. Although only a
few exemplary embodiments of this invention have been described in
detail above, those skilled in the art will readily appreciate that
many modifications are possible in the examples without materially
departing from the novel teachings and advantages of this
invention. For example, features described in relation to one
example may be incorporated into any other example of the
invention.
[0141] Accordingly, all such modifications are intended to be
included within the scope of this invention, which is defined in
the following claims and all equivalents thereto. Further, it is
recognized that many embodiments may be conceived that do not
achieve all of the advantages of some embodiments, particularly of
the preferred embodiments, yet the absence of a particular
advantage shall not be construed to necessarily mean that such an
embodiment is outside the scope of the present invention. As
various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all
matter contained in the above description shall be interpreted as
illustrative and not in a limiting sense.
* * * * *